Controlling system for lifts



Nov. 15,1938. A, A, CHUBB 2,137,075

CONTROLLING SYSTEM FOR LIFTS Filed Sept. 17, 1936 4 Sheets-Sheet lATTOE/VEV Nov. 1 5, 1938. A CHUBB 2,137,075

CONTROLLING SYSTEM FOR LIFTS Filed Sept. 17/1936 4 Sheets-Sheet 2 X r ma O QJA. U K

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Nov. 15, 1938.

A. A. CHUBB CONTROLLING SYSTEM FOR LIFTS nnl Filed Sept. 17, 1936 ECQGLI'INRITIPS? 4 Sheets-Sheet 4 5 Y VA D D V5 (U 1) Patented Nov. 15, 1938UNETED STATES @ATENT OFFER signor to The General Electric CompanyLimited, London, England Application September 17, 1936, Serial No.101,221 In Great Britain September 18, 1935 11 Claims.

This invention relates to electro-magnetic systems of lift control, andhas for its object the provision of means whereby the levelling of thelift at a floor is rendered substantially independent of the loadcarried in the lift car.

As is well known, lift driving motors operated from alternating currentsupplies do not easily afford a wide range of speed control. Thus, for

example, the pole changing type of machine, w though it enables acertain set of speeds to be obtained, does not easily permit a smoothchange from one speed to another. This smooth change is essential in thecase of a motor operating a u lift, preferably during acceleration aswell as during deceleration.

According, therefore, to the present invention, a lift driving motoroperated by alternating current functions in conjunction with an eddycurrent brake, the extent of energization of the brake being dependenton the load. in the lift, this load being measured by the time taken forthe lift to pass between certain predetermined points during thedecelerational period.

H In one embodiment of the present invention, an alternating currentinduction motor driving a lift is started in either direction by meansof the normal slip-ring method. When deceleration on approaching a flooris required, the maximum value of eddy current braking is applied, andsoon afterwards resistance is inserted in the rotor circuit of themotor, this causing the car to decelerate. It should here be noted thatthe value of the resistance in the rotor circuit is con- V stant for allloads.

After a short period of deceleration the lift is timed in its passagebetween two fixed points in the lift shaft. If the load in the lift isone helping the motor to drive, the passage of the car between thepoints is rapid.

Conversely, if the load is a hindering one, the lifts passage isrelatively slow. According to the time taken by the lift in this passagebetween the said two points, resistance is inserted in the M fieldcircuit of the brake, so that in the case of c a helping load, nearlyfull energizaticn is main.- tained, whereas for a hindering load thebraking is reduced. By this means, the lift reaches the required floorlevel at approximately the same 50 creeping speed whatever the load, andcan therefore be stopped at the floor with great accuracy by a furtherfriction brake employed for the purpose. If necessary, a slightover-compounding may be effected by .55 values so that the lift arrivesat a floor with suitable choice of resistance (or. rite- 152) slightlygreater creeping speed with a hindering load than with a helping one.

The sequence of operations is governed by means of one or more inductorrelays situated on the lift car, co-o-perating with a sequence switch ofthe step-by-step variety, the contact banks of which are interconnectedwith various controlling relays. The timing of the lift is performed bya further step-by-step switch which during the timing period rotates ata fixed rate.v The points between which the lift is timed are marked byinductor plates situated in the lift shaft at places reached and. passedby the lift prior to its arrival at any required floor. Connectionsbetween the inductor relay and the sec-- 0nd or timing switch are suchthat passage of one plate initiates switch stepping and passage ofanother plate arrests switch motion. The switch contact banks areconnected to resistances which are inserted between a transformer and arectifier supplying the eddy current brake magnet field coils,variations in the switch position causing variations in the currentflowing through the braking field.

One arrangement in accordance with the invention will now be describedby way of example with reference to the accompanying diagram-- maticdrawings, of which Figures 1 and 1A com bined show a circuit diagram ofthe electrical connections of the gear and Figures 2 and 2A show a codediagram for the readier understanding of Figures 1 and 1A.

In the drawings, the lift motor comprises a, stator ST connected throughcontactor contacts to the three-phase supply mains, and a rotor R0connected through slip rings to starting resistances. An eddy-currentbrake EB and a friction brake BK operate on the motor shaft, and thisshaft is arranged to drive the lift carriage LC through any suitableform of gearing. The eddy-current brake EB is energized through therectifier RA from the transform-er TR, and the friction brake is removedfrom the driving shaft when its coil is energized through the rectifierRC.

Two step-by-step switches of a known type and as used in telephonesystems are used in the controlling circuit. These switches comprisemagnets A and B and contact banks A1, A2, A3 and B1, B2, B;respectively. The switch A used as a sequence controller, and the switchB acts as a timing device to measure time taken by the lift to passbetween fixed points in the shaft.

It is proposed to describe the operation of the system by means of atypical traverse of the lift. The control mechanism is shown as beinghand-operated, the switches CSU and CSD being operable by hand from thelift car. Closure of switch CSU causes the lift to travel up, and CSDcauses the lift to travel down. Whenever the starting handle is movedaway from the normal ofi position, contact CS is broken, no matter whatdirection of travel is required. All apparatus is shown in a normalposition, i. 0. one in which the apparatus rests when the lift is at afloor and all the gates are closed. Under these conditions the relay GLis operated, since its circuit includes the emergency stop button ES andthe gate locks GA GB and (30. Its contacts are shown in operatedpositions.

Assuming that the lift operator closes contact CSU (and consequentlyopens contact CS), a circuit is completed from the positive of contact 91, via contacts rm, v3, n1, CSU, UL the upper limit switch, which isnormally closed and ddi to relay UD which operates.

udl prevents false operation of the relay DD which drives the lift inthe opposite direction.

udz locks UD operated, so that it is not released when contact us openslater.

udg prepares to operate relay C.

U6 4 opens a self-interrupting circuit of the switch magnet A.

uds operates the gate lock catch RCR and prepares a locking andoperating potential for other relays later. Relay SC is also operatedthrough bank A2.

ude breaks a self-interrupting circuit for the switch magnet B.

14617 and lLds apply current to the stator windings ST and to the brakemagnet BK.

801 and so: short-circuit resistances in the rotor circuit used fordeceleration.

8C3 prepares to operate relays V and VA.

On removal of the friction brake BK from the driving shaft, the liftcommences to move, a large starting current being induced in thewindings of the rotor R0. A potential derived from a rotor winding isapplied via transformer and the rectifier RB to the relay VS, whichoperates immediately its contact cs1 operating relay VA from positive oncontact 303. Contact var locks VA operated, contact 'UCLz prepares tooperate relay V later, and contact Dds reduces the current through relayVS. As the rotor speed increases, the rotor currents decrease, so thatafter a short interval the potential applied to VS is reduced to such anextent that this relay releases. Contact 2731 now operates relay V, thecontacts 121 and of which short circuit resistances in the rotor circuitand the machine runs up to full speed.

The lift continues to travel in the shaft until some distance ahead ofthe floor at which it is required to stop. At this point, the switch CSUis opened, and the contact CS closes. Nothing happens until an inductorplate in the shaft is passed, which operates relay Z momentarily, relayUD being held operated by its contact mix. This inductor relay Z, inclosing contact Z1 momentarily operates relay PS.

ps1 locks relay PS operated to Ztds.

ps2 prepares an operating path for relay C.

A series of plates is now passed by the inductor relay Y, each plateoperating the relay momentarily. Each of these operations pulls up andreleases relay C. When the first of this series of plates isencountered, relay C operates.

01 energizes the switch magnet A but the switch, being of the reversedrive type, does not yet take a step.

c2 operates relay EC from uds via bank A3.

801 locks relay EC operated to M15.

(202 applies full potential to the eddy-current brake EB via therectifier RA from the first contact of the switch bank B3 and thetransformer TR.

Release of relay C on passage of the first plate de-energizes thedriving magnet A, and the switch takes a step forward. The current inthe. eddy-current brake begins to rise, causing a progressivedeceleration against the drive of the motor. This must not, however, becontinued for long, as the motor would proceed to draw a large over-loadcurrent from the supply. Another plate is now passed by the relay Y, andon operation and release of relay C for the second time, the switchreaches the third contact in its banks. Wiper A2 breaks the connectionto relay SC and this relay releases.

s01 and $02 open short circuits across resistances in the rotor circuit.

so; releases relays V and VA.

in and 122 open short circuits on further resistance in the rotorcircuit, and both stator and rotor currents are reduced to a valueappreciably below that of starting, so that the motor drives the liftagainst the eddy-'cmrent brake with only a very reduced effort.

The lift is now allowed to decelerate for a short space until the effectof the load in the lift is appreciable. Another plate is now passed byrelay Y, and C operates for a third time. Closure of contact 02 operatesrelay M through wiper A3.

m1 locks relay M operated.

m2 applies positive from udt via bank B1 to the switch magnet B and therelay N, operating both.

The contact 111 of relay N performs a. function which will be describedlater. Operation of the magnet B opens the interrupter contacts db andrelay S operates in series with the resistance X. Contact .91 nowreleases magnet B and the switch takes a step, closing the contacts dband short circuiting relay S which also releases. This cycle of mutualinterruption between S and B continues, the switch (wipers of B1, B2,B3) being driven at a uniform and predetermined rate over its contacts.The wiper of B3 in moving over its bank inserts resistance in thecircuit of the eddycurrent brake, reducing its effectivenessprogressively.

This condition continues until a further plate is pased by relay Y. Thetime of transit between the plates is naturally dependent on the load inthe lift, since if this load is a helping one, the passage of the liftbetween the plates is fairly rapid. If on the other hand, the load is ahindering one, the passage between the plates is longer than normal, andthis passage time determines the extent of travel of the switch B. Ifthe load is a helping one the brake energization must be large in orderto cause adequate speed reduction, and conversely if the load is ahindering one, considerably less braking is required. Assuming that theload is a helping one, then the switch B takes a few steps only,inserting a small amount of resistnace in the circuit of the brake EB.The second timing plate is then passed by the inductor Y, and operationof relay C causes the application of potential from contact 02 via bankA3 and contact on to the second coil of relay M, short-circuiting it.Release of the relay cuts the circuit of the self-interrupting cycle ofS and B at contact 1212, and the switch B remains positioned for theremainder of the lifts travel. Release of relay C allows the magnet A tode-energize and step the switch to the fifth contact.

The lift now decelerates under the influence of a braking force which isproportional to the load in the lift. If necessary, the effect ofovercompounding can be obtained so that the lift when it reaches adistance of a few inches from the floor at which it is required to stop,has a slower creeping speed with a helping load than with a hinderingload. This enables more accurate levelling to be made with the frictionbrake BK than if exactly the same speed is reached during decelerationindependently of the load.

When a point a few inches ahead of the required floor is reached, thelast plate is encountered by the inductor Y, and C is energized for thelast time. Contact 01 energizes the magnet A and 02 operates the relayNR.

n11 releases relay UD.

udq and uds tie-energizes the stator and both brakes, causing thefriction brake BR to be applied to its sheave and stop the lift at thefloor.

11 114 completes a self-interrupting circuit for the magnet A throughits interrupter contact dot.

uds releases the gate latch relay RCR, and also relays EC, NR and PS.

uds completes a self-interrupting circuit for the relay S and magnet B,and holds relay N operated.

udz breaks the holding circuit of relay UD.

uds opens the circuit of C, previously broken by ps2.

01 de-energizes the magnet A, and enables the switch to step to itsfirst contact by self-interruption, when the stepping circuit is brokenby wiper A1 and the switch stops.

The relay S and magnet B from positive through bank B2 interrupt eachothers circuits as previously described, stepping the switch B until itswiper B2 rests on the first contact, when the stepping circuit isbroken. During this time, relay N is held operated, and its contact inprevents operation of either of the driving relays UD or DD, so that thelift cannot be started until this timing switch B has reached a zeroposition, when the relay N releases.

In the meantime, the gate is opened, and one of the gate contacts GA-GCreleases relay GL the contacts 911 and 912 of. this relay preventingoperation of either of the driving relays or of relay C until reclosureof the gates.

From the foregoing it will be seen that a measurement of the load in thelift has been effected by measuring the time taken by it to pass betweentwo fixed points or plates in the shaft. During normal travel from onefloor to a distant one, both inductor relays Y and Z are operated by thepassage of plates in the shaft, but their contacts are prevented fromcausing any action by the open condition of contacts ps2 and CS, untilthe handle of the driving switch has been returned to normal by the liftattendant, so that the deceleration process can only be commenced afterthis action has been performed by the operator.

Although my invention has been described in connection with a manuallyoperated lift, it should be understood that it is easily applicable toone in which automatic operation combined with call storage is effected.The only adaptation necessary to fulfil these conditions is that ofputting the relays UD and DD under the control of devices which registercalls in combination with a furtherdevice which follows the movement ofthe lift, these causing suitable operation or closure of the contactsCSU, CSD and CS. These call storage and car following devices arewell-known in the art, and are not described in further detail as theyform no part of the present invention, though it is to be understoodthat the scope of the said invention is intended to cover all obviousmodifications of control of the lift such as that described.

Finally, although in the drawings the bank B3 is shown connecteddirectly to the controlling resistances, it might be necessary toarrange that the switch operated a number of contactors which in turnswitch the resistances in or out of circuit.

I claim:

1. In a lift control system for serving a plurality of floors, a motorfor driving the lift, control means, relays operated by the controlmeans for effecting operation of the motor for up and down travel of thelift, an eddy-current brake arranged to control deceleration of themotor for stopping the lift at a floor, and means including variableresistance controlled by the speed of the lift when approaching thefloor at which the lift is to stop for varying the effect of saideddy-current brake during deceleration, the arrangement being such thatwith a helping load in the lift the speed is greater and the amount ofresistance inserted is less than with a hindering load when the speed isless and more resistance is inserted.

2. In a lift control system for serving a plurality of floors, a motorfor driving the lift, control means, relays operated by the controlmeans for effecting operation of the motor for up and down travel of thelift, an eddy-current brake arranged to control deceleration of themotor for stopping the lift at a floor, resistance for controlling thecurrent to the eddy-current brake while the motor is decelerating, thespeed of the motor during deceleration being controlled by the load inthe lift, and means controlled by the lift for varying said resistanceaccording to the speed of the lift during deceleration.

3. In a lift control system for serving a plurality of floors, a motorfor driving the lift, control means, relays operated by the controlmeans for effecting operation of the motor for up and down travel of thelift, an eddy-current brake arranged to control deceleration of themotor for stopping the lift at a floor, a circuit including a tappedresistance for controlling current to the eddy-current brake, switchingmeans cooperating with said tapped resistance for varying the resistancein said eddy-current circuit according to the speed of the lift duringdeceleration, said deceleration speed being determined by the load inthe lift, and a relay operated by the lift for controlling operation ofsaid switching means.

4. A lift control system as in claim 3 wherein said relay operated bythe lift is arranged to be operated by an inductor relay duringdeceleration of the motor, said inductor relay being operated byinductor plates which are passed by the lift.

5. In a lift control system for serving a plurality of floors, a motorfor driving the lift, control means, relays operated by the controlmeans for effecting operation of the motor for up and down travel of thelift, an eddy-current brake arranged to control deceleration of themotor for stopping the lift at a floor, a circuit including a tappedresistance for controlling current to the eddy-current brake, astep-by-step switch cooperating with the tappings of said resistance forvarying the resistance in said eddy-current circuit, automatic impulsingmeans for stepping said switch at a fixed rate during deceleration andrelay means controlled by the lift for starting and stopping thestepping of said automatic impulsing means when the lift reachesprearranged distances from the floor at which it is to stop.

6. A lift control system as in claim 5 wherein an inductor plate relayarranged to be operated during deceleration by a plurality of inductorplates controls the starting and stopping of said automatic impulsingmeans.

7. A lift control system as in claim 5 wherein a ,step-by-step sequenceswitch is arranged to start and stop operation of said automaticimpulsing means, and a relay arranged to be actuated by the liftcontrols the stepping of said sequence switch.

8. In a lift control system for serving a plurality of floors, analternating current motor for driving the lift, resistance coils in therotor circuits of the motor, control means having an off position,relays arranged to be energized by operation of the control means foreffecting operation of the motor for up and down travel of the lift, aneddy-current brake for controlling the motor during deceleration, asequence relay arranged to be operated by the lift while travelling to astop at a floor, and only when said control means is in its offposition, for controlling operation of said brake, sequence step-by-stepswitching means controlled by said last named relay,

relays controlled by said sequence switching means and operatingcontacts for short circuiting and inserting said rotor resistances, thearrangement being such that said resistances are short-circuited atnormal speed of the motor and inserted during deceleration when saideddy-current brake is operated and an inductor plate relay arranged tocooperate with a plurality of inductor plates in sequence for operatingsaid sequence relay.

9. A lift control system as in claim 8 wherein additional lift inductorplate operated relay means controlled by said control means and operableonly when the latter is in its oil position is provided for preparing anoperating circuit for said sequence relay.

10. A lift control system as in claim 8 wherein a tapped resistance isprovided for controlling current to said eddy-current brake and anautomatically stepping switch for controlling insertion of saidresistance is provided, the starting and stopping of which is arrangedto be controlled by said sequence relay.

11. A lift control system as in claim 8 wherein there is provided anelectromagnetically operated holding brake cooperating with the motorshaft, said brake being arranged to be released upon efiecting operationof the motor by energization of said up and down relays and to becomeeffective to stop and hold the motor when said relays are deenergized.

ALEXANDER ALBERT CHUBB.

